In order to achieve data transmission correctly in time, signals for synchronizing between transmitter and receiver must also be sent out on a bus.
In known apparatus, as for example in the LM Ericsson Company Description identified by catalogue code X/Yg 118909 Ue relating to the regional processor bus in an AXE 110 telephone exchange, separate clock equipment is utilized for the bus, which means that the information is intentionally delayed and clocked out on the bus with the aid of a separate clock signal unit.
For a combination of transmitter and receiver in the same module, in the above-indicated known apparatus there are required separate clock signals and possibly clock oscillators in both transmitters and receivers for synchronizing with respect to the bus. This results in delay in the information transmission, poor capacity utilization on the bus and a complicated hardware structure. Furthermore, it is difficult to achieve great reliability with central feeding of clock signals.